I was playing with a friend and a situation that we have never encountered before came up and I am just looking for some clarification

My plot is threat from the north and I play flame kissed on one of my opponents characters at which point it's strength is 0 does the character go to the discard pile for threat from the north or the dead pile for flame kissed or do I get to choose which pile it goes to.

As with all passives that try to resolve at the same time but can't, the First Player decides the order. Practical result in this case is that the First Player decided whether the character is discarded by Threat or killed by Kissed before the other one gets a chance to try and fail.